Method of making balls



March 16, 1943. u. JELINEK l 2,313,876

METHOD OF MAKING BALLS Filed June 18, 1940 WITNESSES: INVENTOR mm W? Patented Mar. 16, 1943 UNITED STATES PATENT OFFICE 2,313,876 mhrnon or MAKING BALLS Ulrich- Jelinek, Elizabeth, N. L, assignor to Westinghouse Electric .3; Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 18, 1940, Serial No. 341,100

9 Claims.

position of the ball, but they have one or more of the disadvantages of rust formation, lack of sufllcient hardness and toughness to give a long life, or the cost of the ball is commercially prohibitive.

An object of this invention is to provide a method of producing balls of stainless steel.

A more specific object of this invention is to provide a method of producing a ball by coldworking high carbon stainless steel to the desired shape and giving it a surface finish free from imperiections at a magnification of at least 54 diameters.

Other objects of this invention will be apparent from the following description when taken in conjunction with the accompanying drawing, in which:

Figure 1 is a view in elevation of a slug utilized in this invention;

Fig. 2 is a view in section of the slug of Fig. 1 taken along the line II--II thereof;

1 Fig. 3 is a view in elevation and partly in section of upsetting dies and a slug as utilized in this invention;

Fig. 4 is a view in elevation and greatly exassented oi the slugafter it has been formed to the approximate shape and size of the desired ball in accordance with the teachings of this invention;

Fig. 5 is a view in elevation and partly in section of a rotating tumbling barrel employed in practicing the method of this invention; and

Fig. 6 is a view in elevation of a steel ball produced in accordance with this invention.

In practicing this invention, it is preferred to employ a hard stainless steel having a compositicn of between .9% and 1.1% of carbon, from 17% to 19% of chromium and the balance substantially all iron. In addition to the essential elements of carbon, chromium and iron, impurities such as not more than .65% of manganese, not more than .5% of silicon and not more than 035% of each of phosphorus and sulphur may be present without detrimentally affecting the characteristics of the steel. This preferred stainless steel is quite tough and in the hardened condition has a Rockwell C hardness of 63 as compared with the Rockwell C hardness of from 64 to 66 for tool steel.

In order to deform the stainless steel as sup plied by the manufacture into the balls of this invention, it has been found desirable to form the steel into wire of predetermined-size depending upon the size of the balls which are to be manufactured therefrom. However, since the steel is quite hard, in order to conserve and prolong the life of the dies utilized in forming the steel into wire of predetermined size, the stainless steel is coated with a die lubricating metal suchas copper or cadmium. The coating of die lubricating metal need not be excessive, it being found that a coating having a thickness of .0001

inch is satisfactory as the lubricant. Copper is preferred as the die lubricating metal since it can be readily applied to the steel in a number of known commercial ways. Further copper is comparatively inexpensive.

Even with the coating of die lubricating metal applied to the steel, it is found that the steel is too hard for commercially reducing it to any predetermined size of wire or rod. It. is, therefore, necessary to anneal the coated wire to a tensile strength of from 90,000 to 110,000 pounds per square inch. This change inthe tensile strength in the steel can be obtained by any suitable annealing technique,-an example of which is to heat the steel to approximately 1350 F. for a period of time from four to six hours, after which the steel is permitted to cool very slowly in the furnace.

With the steelsuitably annealed as described and coated with the die lubricating metal, copper, the steel is passed through suitable dies to effect a substantial reduction in area of the wire. In reducing the steel to a wire of any given :predetermined size, it is found that a reduction of from 10 to 20% in area so increases the hardness of the stainless steel that an intermediate annealing operation must be performed before subjecting the steel to further reduction in area. The re-anneal may be a heat treatment similar to that described hereinbefore for reducing the tensile strength of the steel. If swaging dies are employed, it is possible to effect a reduction in area of the steel ranging up to as much as in one pass. Alternate annealing of the wire and passing it throughthe die to eifect further reductions in area are practiced until the desired size of 'wire is obtained.

five minutes. after which the excess acetone is removed therefromand, if desirable, a further treatment in the acetone may be applied to the balls to ensure removal of all water and polishing compound therefrom. The acetone is then evaporated from the balls by any suitable means such as by heating the balls in oven for of pulverized corn cob and shreads of chamois in another tumbling barrel which has been lined with a good grade of cloth such as velveteen. The rotation of the balls in the presence of the mixture of corn cob and chamois ensures clean-- lines and luster to the surface of the high carbon stainless steel balls. I

By practicing the teachings of this invention it has been found possible to cold upset slugs of high carbonstainless steel to form the steel into the approximate size of desired balls without damage to the balls or to the upsetting dies. Further bythis method a very highly polished stainless steel ballis obtained, which, ,because of its composition, is very hard and tough, the

combination of the polish and the characteristics of the steel giving an extremely long life to the resulting balls. In all cases the balls will have a surface finish free from imperfections at a magnification of at least 54 diameters and a hardness of from 58 to 64 Rockwell C. Although in the specific example referred to hereinbefore, a surface finish free from imperfections at a magnification of 175 diameters was obtained, balls have been produced by continued polishing which have such a high polish that their surfaces are free from imperfections at a magnification of 600 diameters. The stainless steel balls produced in accordance with this invention are, therefore, far superior to the high carbon steel balls or balls of other compositions utilized in the bearings of watthour meters prior to this invention.

Although this invention has been described with reference to a specific embodiment thereof, it is, of course, not to be limited thereto except insofar as is necessitated by the prior art and the scope of the appended claims.

I claim as my invention:

1. The method of producing stainless steel balls having a carbon content of from .9% to 1.1% comprising the steps of, coating the stainless steel with a die lubricating metal, annealing the coated steel to give it a tensile strength of between 90,000 and 110,000 pounds per square inch, forming the stainless steel into slugs of a predetermined size having a coating of lubricating metal on at least the peripheral portion thereof, cold pressing the coated slugs into balls of approximately the finished size, subjecting the cold pressed balls to a grinding operation to remove the lubricating metal therefrom and provide the balls with a surface having a unifom roughness, and polishing the balls with a polishing compound to give the balls a surface finish free from imperfections at a magnification of at least 54 diameters.

2. The method of producing stainless steel balls having a carbon content of from .9% to 1.1% comprising the steps of, coating the stain f 3 less steel with a die lubricating metal, annealing the coated steelto give it a tensile strength of between 90,000 and 110,000 poundsper square inch, forming the annealed steel into slugs of a predetermined size having a coating of lubricating metal on at least the peripheral portion thereof, annealing the formed slugs to impart a tensile strength of between 90,000 and 110,000 pounds persquare inch to them, cold pressing the coated slugs into balls of approximately the finished size, subjecting the cold pressed balls to agrinding operation to remove the lubricating metal therefrom and provide the balls with a surface having a substantially uniform roughness, and polishing the balls with a polishing compound to give the balls 9. surface finish free from imperfections at a magnification of at least 54 diameters.

3. In the method of producing balls from high carbon stainless steel, in combination, coating the stainless steel with a die lubricating metal, annealing the steel to give it a tensile strength of between 90,000 and 110,000 pounds per square inch, forming the steel into slugs of predetermined size having a coating of die lubricating metal thereon, ing the coating thereon in the cold state to form the slug into the approximate shape of a ball, and grinding andpolishing the ball formed by the cold upsetting to remove the coating of lubricating metal and give the ball a desired size and surface finish.

4. The method of producing stainless steel balls having a carbon content of from .9% to 1.1% comprising the steps of, coating the stainless steel with a die lubricating metal, annealing give it a tensile strength of inch, forming the stainless steel into slugs of apredetermined size having a coating of lubricating metal on at least the peripheral portion thereof, cold pressing the coated slugs into balls of approximately the finished size, subjecting the cold pressed balls to a grinding operation to remove the lubricating metal therefrom and provide the balls with a surface having a uniform roughness, and polishing the balls with a polishing compound including aluminum oxide to give the balls a surface finish free from imperfections at a magnification of at least 54 diameters.

5. The method of producing stainless steel balls having a carbon content of from .9% to 1.1% comprising the steps of, coating the stainless steel with a die lubricating metal, annealing the coated steel to give it a tensile strength of between 90,000 and 110,000 pounds per square inch, forming the annealed steel into slugs of a predetermined size having a coating of lubricating metal on at least the peripheral portion thereof, annealing the formed slugs to impart a tensile strength of between 90,000 and 110,000

pounds per square inch to them, cold pressing upsetting the slugs of steel hav-' 4- less steel witha die lubricatinglmetal, annealing the coated steel to give it a tensilestrength of between 90,000 and 110,000 pounds per square inch, forming the stainless steel into slugs of a predetermined size having acoating of lubricating metal on at least the peripheral portion thereof, cold upsetting the coated slugs into balls of approximately the-finished size, subject: ing the cold pressed balls-to a grinding operation to remove thelubricating metal therefrom and provide the balls with asurface having a uniform roughness, and polishing the balls by rotating them in a sodium carbonate solution containing aluminum oxide to give the balls a surface finish free from imperfections at a magnification of at least 54 diameters.

7. The method of producing stainless steel balls having a carbon content of from .9% to 1.1% comprising the steps of, coating the stainby cold heading the slugs along their length into.

balls of approximately the finished size, subjecting the cold-headed balls to a grinding operation to remove the lubricating metal therefrom and provide the balls with a surface having a substantially uniform roughness, and polishing the balls by rotating them in a polishing compound containing aluminum oxide to give the balls a surface;finlsh free from imperfections at a magnification of atleast 04 diameters.

8. The method of producing balls from high carbon stainless steel comprising the steps of. coating the stainless steel with a die lubricating 'metal, alternately annealing the steel to give it a tensile strength of between 90,000 and 110,000 pounds per square inch and eifecting a reduction in cross sectional area to produce a steel wire of predeterminedsize, cutting the wire into slugs of apredetermined size having a coating of the "lubricating metal on at least the peripheral portion thereof, cold pressing the coated slugs into balls of approximately the finished size, and grinding and polishing the balls formed by thecold upsetting to remove the coating of lubricating metal and give the balls a required size and surface finish.

9. The method of producing balls from high carbon stainless steel comprising the steps of, coating the stainless steel with'a die lubricating metal, annealing the coated steel to give it a tensile strength of between 90,000 and 110,000 pounds per square inch, forming the steel into slugs of a predetermined size having a coating of lubricating metal onat least the peripheral portion thereof, cold pressing the coated slugs into balls of approximately the finished size, subjecting the cold pressed balls to a grinding operation to remove the lubricating metal therefrom and provide the balls with a surface having a substantially uniform roughness, heat treating the balls to impart hardness thereto,

and polishing the balls with a polishing compound to give the balls a surface finish free from imperfections at a magnification of at least 54 diameters.

ULRICH JELINEK. 

